Iron-induced oxygen radical metabolism in waterlogged plants

Roots of the iron-sensitive wetland plant, Epilobium hirsutum L., respond to oxygen-depletion by enhanced uptake of ferrous ions. Evidence is presented for an iron-catalyzed reaction within roots leading to super oxide radical formation and the induction of superoxide dismutase. The immediate product, H2O2, appears to accumulate in the absence of catalase and low activity of root peroxidases, resulting in hydroxyl radical formation, inhibition of protein synthesis, increased lipid peroxidation and gross cellular damage. Evidence for alternative 'healthy' responses is given. A scheme is presented which outlines a biochemical mechanism for iron-mediated flood or waterlogging tolerance and intolerance in plants.